I know how to fix this by reconfiguring Opera, but can anyone tell me in words of one syllable if there's something I can put in the svg file header to stop it happening? I tried cachecontrol="nocache" which I thought should work but it didn't help.
Hoping I can do it at this level - telling all users to reconfigure their browsers won't be much of a solution, and I'd rather not require complicated Apache configuration since I'm doing this for a third party - the more configuration which is under my control, i.e. being written to the browser by my code, the better